Suppressing a short channel effect in a MISFET (Metal Insulator Semiconductor Field Effect Transistor) is a problem associated with shrinking the size of the MISFET.
One way to suppress the short channel effect is to form a Halo structure in the MISFET.
A MISFET with Halo structure is disclosed in U.S. Pat. No. 6,743,684. In the MISFET in U.S. Pat. No. 6,743,684, the Halo structure is formed by ion implanting an impurity ion into a substrate below a gate electrode.
However, in the MISFET of the art, the impurity ion is implanted in a broad area in the semiconductor substrate, so it is difficult to obtain a Halo structure in the required portion.
So a region where the Halo region and the source/drain region overlap each other may be increased, and a junction leak current may occur and a junction capacitance may be increased.